Introduction of Na into Cu2SnS3 thin film for improvement of its photovoltaic performances
Introduction of Na into Cu2SnS3 thin film for improvement of its photovoltaic performances
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DOI：
10.1016/j.solmat.2017.04.040
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发表时间：
2017-08
影响因子：
6.9
通讯作者：
Jakapan Chantana;Koichi Suzuki;T. Minemoto
中科院分区：
文献类型：
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作者：
Jakapan Chantana;Koichi Suzuki;T. Minemoto
研究了Na对Cu 2SnS 3（CTS）薄膜物理性能和光伏性能的影响。采用NaF/Cu/SnS 2叠层前驱体硫化法制备了CTS薄膜。使用NaF前体作为用于将Na引入到CTS膜中的主要Na源。结果表明，随着NaF前驱体厚度的增加，CTS膜中Na含量增加，Na/Cu原子比增加，Cu/Sn原子比降低。这表明在Cu/SnS 2叠层前体上添加NaF覆盖层抑制了硫化过程中Sn-S化合物从样品中蒸发，从而形成Sn 2S 3二次产物。因此，对于过厚的NaF层（大于或等于75 nm），在所得CTS膜的本体和近表面中严重形成对电池性能具有不利影响的Sn 2S 3第二相。然而，CTS的晶粒尺寸显着扩大的NaF前体的厚度增加。结果表明，当NaF厚度为60 nm时，具有减反射层的CTS薄膜太阳能电池的转换效率提高了4.8%，这是因为在表面附近获得了没有Sn 2S 3第二相的单相大晶粒CTS吸收层，从而提高了开路电压和归因于载流子复合减少的填充因子。
Impact of Na in Cu2SnS3(CTS) films on their physical properties and photovoltaic performances is investigated. CTS films are fabricated by sulfurization of NaF/Cu/SnS2stacked precursors. NaF precursor is used as primary Na source for Na introduction into the CTS films. It is demonstrated that Na content in the resulting CTS films is increased with enhancing thickness of NaF precursor, leading to the increase in Na/Cu atomic ratio but decrease in Cu/Sn atomic ratio. This suggests that the addition of NaF capping layer on the Cu/SnS2stacked precursors suppresses evaporation of Sn-S compounds from the sample during sulfurization, thus forming Sn2S3secondary. Therefore, with too thick NaF layer (greater than or equal to 75 nm), Sn2S3secondary phase in bulk and near surface of the resulting CTS films, having the detrimental effect on cell performances, is severely formed. However, the CTS grain sizes are notably enlarged as the thickness of NaF precursor increases. As a result, conversion efficiency of CTS thin-film solar cell with anti-reflective layer is increased up to 4.8% with the optimized NaF thickness of 60 nm since the single-phase and large-grain CTS absorbing layer without Sn2S3secondary phase near the surface is attained, thereby increasing open-circuit voltage and fill factor attributed to the decrease in the carrier recombination.